水中矩形板的共振声辐射

研究共振声辐射理论(Resonance Radiation Theory:RRT)在水中矩形板的应用。导出了矩形板的共振声辐射公式、并数值验证了其适用性。深入分析了有流体负荷矩形板的复共振频率的物理意义及其与导纳留数、模态辐射率的关系,复共振频率的实部表示实际共振频率,虚部反映模态辐射能力。根据复共振频率容易找到辐射能力相对较强的模态,为有针对性控制声辐射提供了新的思路。鉴于复平面搜根求解模态复共振频率的困难,针对矩形板的特点提出了一种求解复共振频率及留数的快速方法。结合该方法及RRT,提出了一种快速计算辐射声功率的方法,数值验证表明该方法精度高、速度快。     

风速测量实验的设计与探究

基于电磁理论和空气动力学的相关知识,利用磁铁、金属棒和DISLAB传感器等器件设计并制作了风速测量系统,可准确地测量2-11级范围内的风速值.该装置还可作为演示电磁感应现象的设计型实验内容,实验过程中可加深学生对电磁感应现象的理解,并提高学生对matlab软件的应用能力.     

丽江玛咖的营养成分分析及多糖体外的抗氧化作用

对丽江种植区玛咖（Lepidium meyenii Walp）的营养成分进行分析,其含有丰富的蛋白质、碳水化合物、矿物质、维生素、脂肪酸和氨基酸等,并通过试验证明玛咖多糖体外具有一定的抗氧化保健作用,为丽江玛咖成功引种和进一步的研究开发提供依据.     

Influence of structural defects on the optical properties of strongly coupled Au nanoshell arrays

The effects of different defects on optical properties and plasmon resonances properties of Au nanoshell arrays were investigated by using the finite-difference time-domain(FDTD) theory.It is found that the optical properties of the nanoshell arrays are strongly influenced by different defects.We show that when the hollow Au nanoshell arrays are placed in air,there is a wide photonic band gap(PBG) in the infrared region,but the band gap becomes narrower as we introduced different defects.Based on the distributions of electric field component E z and the total energy distribution of the electric and the magnetic field,we show that there exhibit dipoles field distributions for the plasmon mode at the long-wavelength edge of the band gap,but composite higher order modes are excited at the short-wavelength edge of the band gap.The plasmon resonant modes also can be controlled by introducing defects.     

Accelerated steered response power method for sound source localization via clustering search

The steered response power-phase transform (SRP-PHAT) sound source localization algorithm is robust in a real environment. However, the large computation complexity limits the practical application of SRP-PHAT. For a microphone array, each location corresponds to a set of time differences of arrival (TDOAs), and this paper collects them into a TDOA vector. Since the TDOA vectors in the adjacent regions are similar, we present a fast algorithm based on clustering search to reduce the computation complexity of SRP-PHAT. In the training stage, the K-means or Iterative Self-Organizing Data Analysis Technique (ISODATA) clustering algorithm is used to find the centroid in each cluster with similar TDOA vectors. In the procedure of sound localization, the optimal cluster is found by comparing the steered response powers (SRPs) of all centroids. The SRPs of all candidate locations in the optimal cluster are compared to localize the sound source. Experiments both in simulation environments and real environments have been performed to compare the localization accuracy and computational load of the proposed method with those of the conventional SRP-PHAT algorithm. The results show that the proposed method is able to reduce the computational load drastically and maintains almost the same localization accuracy and robustness as those of the conventional SRP-PHAT algorithm. The difference in localization performance brought by different clustering algorithms used in the training stage is trivial.     

Precise absolute positioning for a single-frequency user

A new strategy to realize precise absolute positioning for a single-frequency user is presented. In the presented strategy, the receiver clock and ambiguities are removed using the satelliteand epoch-differenced (SDED) algorithm. As a further development of the SDED algorithm, a regional augmentation network is used to generate the SDED atmospheric delays at the user. The weakened mathematic property due to the epoch-differenced operation is improved by adding the generated atmospheric delays and applying the robust estimation. To test the new approach, the 24-h data at 5 Continuous Operation Reference Station (CORS) stations in Shanghai is processed. The results show a more than 96% success rate, defined as the case where three directions achieve the desired positioning accuracy of 10 cm, when the observation is longer than 20 min. The 20-min static results show that the new method can reach an accuracy of 3.42, 4.76 and 9.26 cm in the North, East and Up directions, respectively. An experiment was carried out to assess the kinematic positioning. The results show that the kinematic positioning accuracy is 4.11, 5.31 and 4.05 cm in the north-south, east-west and height directions,respectively.     

反相高效液相色谱法测定小鼠脑中的梓醇

建立了小鼠脑组织中梓醇的反相高效液相色谱检测方法.色谱柱为Agilent Zorbax SB-AqC18亲水色谱柱,流动相为水-乙腈(99.5:0.5,V/V).流速为1.0mL/min,检测波长为210nm,柱温为30℃.梓醇含量在0.8-40.8μg/mL范围内线性关系良好,相关系数r为0.9999.平均回收率为70.0％-77.4％,RSD≤5.9％.按照5mg/kg给药剂量,C57小鼠腹腔注射梓醇,结果显示2h后,0.29％的给药量可以通过血脑屏障进入脑组织.所建立的RP-HPLC法简便,快速,准确,可靠,能较好的应用于小鼠脑组织中梓醇的测定.     

编码光系统的颜色耦合与颜色失衡校正

为了减小编码光系统中的颜色耦合与颜色失衡的干扰,提高形状与颜色重建的准确度,建立了彩色编码光系统,并对其所采用的编解码方法、颜色重建的两个相关环节及颜色校正方法进行了研究。首先,给出了系统的彩色梯形相移强度比编解码法,分析了编解码过程中存在的RGB基色相互耦合现象,设计了应用Caspi模型硬件标定的颜色耦合校正方案;然后,给出了系统的逐点颜色重建法,分析了颜色重建过程中由表面曲率导致的颜色失衡现象,设计了利用表面几何信息校正颜色失衡的方案。实验结果表明：校正后单一绿色图像中的红色分量值约为校正前的1/10;单色表面色差约为0.1,趋近于人眼颜色分辨率,远低于校正前的0.4;重建的单色复杂被测表面颜色均匀、视觉效果良好,符合实际情况。提出的方法符合编码光系统抗干扰能力强的要求,有助于提高形状与颜色重建的准确度。     

超高速碰撞2A12铝板产生闪光辐射的空间演化规律

为了描述超高速碰撞2A12铝板产生闪光辐射的空间演化规律,利用瞬态光纤高温计测量系统并结合二级轻气炮加载系统,开展了弹丸以30°的入射角度和不同碰撞速度条件下的超高速撞击实验。基于闪光辐射强度和辐射温度的实验数据处理得到了超高速碰撞2A12铝板在撞击点附近产生的最大闪光辐射强度和最大闪光辐射温度,基于大量实验,建立了撞击点附近最大闪光辐射的空间演化模型。并结合Origin软件对实验所得数据的拟合,得到了最大闪光辐射强度和辐射温度随探测点到着靶点间距离变化的拟合函数关系式。实验结果还表明:在相近碰撞速度、相同碰撞角度条件下,在同一椭球面上不同探测点位置处的最大闪光辐射强度和最大闪光温度差别不大,验证了撞击产生的闪光辐射以近似椭球的形状向外膨胀,随着等离子体云的向外膨胀,离碰撞点越远产生的最大闪光辐射强度和最大闪光辐射温度均越小;在相同碰撞角度、不同碰撞速度条件下,在同一椭球面上不同探测点位置处的最大闪光辐射强度和最大闪光温度均随碰撞速度的增加而增大。该研究在导弹拦截、天体物理及深空探测领域具有重要的应用价值。     

基于人体血清荧光光谱和改进变量选择方法对血糖浓度测定的研究

利用人体血清240 nm激发波长荧光光谱在220～900 nm波段针对血糖浓度进行建模分析。在模拟退火算法和偏最小二乘算法的基础上进行建模波长变量筛选方法的改进。基于变量入选模型统计频率和无关变量消除法,分别进行了波长的初选和精选过程。同时,加入了主成分数自适应特性等加快收敛速度、减小计算量的措施。该模型对比了线性、三次样条函数、高斯函数作为偏最小二乘法插入基函数的情况下,分别对原始光谱、Daubechies小波分解第三层和第四层细节信号光谱建模。结果显示,该模型避免了主成分参数尝试导致的时间成本,在参数自适应的过程中很快趋于稳定并得到对应条件下的最佳建模主成分数。其波长变量筛选能力使得对独立样本的分析预测效果有了显著的提升,最佳建模预测效果达到0.25 mmol·L-1,达到了血糖检测的医用要求。加入了非线性建模条件使得模型有明显的改善,基于样条函数的效果总体最好,其次为基于高斯函数的情况。对原始光谱进行小波分解,得到的细节信号光谱建模效果更为可观。总体而言第四层细节信号光谱建模效果略优于第三层细节信号光谱。模型筛选波长变量的频率意味着在所给实验条件下的血糖浓度信息在不同波段的分布情况,这为血糖在血清成分中的物理化学特性提供了一定程度上的统计解释。